v3.4.0

Minor update with some fixes

• updated Cs NIST data (@petermao in #155 )
• fixed issue with Numpy deprecation (@dehond in #146 )
• fixed issue with missing Cs G 9/2 level missing quantum defects (@johnny-sa in #149 )
• fixed typos in documentation (@petermao in #147 )
• improved error reporting for Wigner coeff. (@petermao #148 )